"Not considered" is one of the forms of the sacrament "considered" adding a negative particle. In the examples used and other forms. Due to this it is much easier to see what rules that is characteristic of the participles in General, apply in a particular case.
Involved in turnover "not" is always written separately from the participle "considered" "not considered them is the difference", "not taken into account in the moment of opportunity." Don't forget to separate the turnover comma if it comes after the main word: "expenses not accounted for in the early days, was reflected in the overall profit."
If the participle with a negation are given in short form (taken into account taken into account taken into account taken into account), "not" is also written separately: "this fact is not taken into account us", "these items are not considered as insignificant". Please note that in such cases the participle in nominative is the predicate.
The third case, when the participle with the particle "not considered" written separately, - the opposition. Examples: "do not take into account the disadvantages, and the forgotten virtues helped us to cope," "not taken into account, and only referred cases", etc.
If the sacrament is given without turnover in the full form, "not" written together: "unreported sum", "unregistered items", etc. This is the only case, when not written together, but found it often enough.
In determining the specific case of an invalid rule regarding adjectives. Don't try to find a synonym without the negation: "the forgotten", "neglected", etc. Communion, for all its similarity with adjectives, are written by completely different rules.